Wood, pvc, aluminium whatever floats your boat, I am going for pvc as the concervatory is hidden at the back of the house where only the cows can comment on it 

https://www.leroymerlin.fr/produits/menuiserie/fenetre-et-porte-fenetre/
Wood, pvc, aluminium whatever floats your boat, I am going for pvc as the concervatory is hidden at the back of the house where only the cows can comment on it 

https://www.leroymerlin.fr/produits/menuiserie/fenetre-et-porte-fenetre/